Manchester United are out on their own when it comes to chasing a game, as they proved once again in coming back from two goals down to beat Braga in the Champions League in midweek, but Sir Alex Ferguson takes his overgenerous defence to Stamford Bridge on Sunday knowing there can be no repeat of last season's drama when they let Chelsea take a three-goal lead before fighting back to claim a point.

This time United are facing a quite different Chelsea – different manager, beefed-up midfield, completely new way of playing and all the confidence that comes from winning the Champions League at long last and being unbeaten at the top of the Premier League going into November. "You have to be impressed," the Manchester United manager says.

"They had to change the way they played because they lost Didier Drogba. They can't go long any more so everything goes through midfield, they have brought in some clever players such as Eden Hazard and Oscar to join Juan Mata and they have managed to fit them all in. This is possibly not the strongest Chelsea side we have come up against – they were a formidable force under José Mourinho, really powerful and ruthless – but it is a successful one because they are top of the league and champions of Europe."

Ferguson not only believes Roberto Di Matteo deserves a lot of credit for the transformation; he could not understand why Chelsea did not make him their permanent manager the minute he made history by winning the club and the capital's first European Cup.

"Roberto has shown this season he is bold enough to be a top manager but winning the Champions League is the strongest recommendation," he says. "I was surprised they didn't give him the job straight away, because winning the Champions League is not easy; it is an achievement that deserves recognition. Chelsea had never won the competition before and their owner clearly regards the Champions League as a holy grail."

By that logic Avram Grant must be the unluckiest Chelsea manager in recent seasons, as he was a John Terry penalty slip from delivering the goods to Roman Abramovich against United in Moscow in 2008, though that was still the Stamford Bridge team that Mourinho built. The same could be said of the one that went out so controversially against Barcelona a year later under Guus Hiddink and, though André Villas-Boas appeared to be brought in with a brief to break up an ageing side and rejuvenate Chelsea, it is Di Matteo who has managed it, even if success against Bayern Munich was the last gasp of the Drogba era.

Frank Lampard can no longer rely on starting now that younger midfielders have been recruited, Michael Essien is out on loan at Real Madrid and Terry is suspended for the United game, so only Petr Cech, Mikel John Obi , Hilário and Ashley Cole remain from the Mourinho years. Chelsea had a good record against United even before Mourinho transformed them into a title-winning outfit – uniquely they have won more of their Premier League meetings than Ferguson's side – and United have not managed a league win at Stamford Bridge in the past decade, although Robin van Persie did score a hat-trick there in Arsenal's remarkable 5-3 victory a year ago.

Now Van Persie is a United player and Javier Hernández appears to be back to his lethal best, Ferguson probably has the best strike force in the Premier League; it is just the midfield and defence that are causing concern, especially with Shinji Kagawa likely to be missing for a month. Ferguson can always withdraw Wayne Rooney to that position and United are always going to be able to create scoring opportunities but Rooney himself, who captained the side against Braga, appreciates that the team cannot keep putting itself under a handicap by going behind.

"We did well to get back in the game and win against Braga but against the best teams it will be more difficult to get those goals," Rooney says. "We certainly don't want to be going one or two down against Chelsea. I know we went three down last season and still drew but we can't afford to do that again."

Rooney is also full of admiration for the way Chelsea have reinvented themselves. "They have started brilliantly and they have brought in some fantastic players," he says. "I think this season they have a lot more pace about them and it's clear that having won the Champions League has given them a lot more confidence.

"Mata is a great player, Hazard has settled in really well and those two, along with Fernando Torres, are the biggest threats. Torres will always be a threat. I don't think he gets the credit he deserves because he works hard for the team and always puts a shift in. Sometimes the goals go in for him, other times they don't but he's always trying."

While most people are predicting a high-scoring game, mainly because United's defence seems incapable of shutting out opponents for 90 minutes, Ryan Giggs would be happy with a low-scoring one.

"The secret of winning leagues and trophies is to win games 1-0 on a consistent basis," the United veteran says. "Clean sheets are very important. You can't go through a season giving opponents one- or two-goal leads, it is something we have got to address and we will do. We know Chelsea have got off to a good start but it's a long season. It is still early in terms of where the title ends up but for Chelsea to be four points ahead of us at this stage makes it an important game."